Digital broadcasting system has become a high-light of research on computer application. To respond to the changes of the playbill in the broadcasting system in real time, the response time of the system must be studi...Digital broadcasting system has become a high-light of research on computer application. To respond to the changes of the playbill in the broadcasting system in real time, the response time of the system must be studied. There is scarcely the research on this area currently. The influence factors in the response time are analyzed; the model on the response time of the system service is built; how the influence factors affect the response time of the system service is validated; and four improvement measures are proposed to minimize the response time of system service.展开更多
In this paper,we study the advantages of cooperation in broadcasting systems from a geosynchronous earth orbit(GEO)satellite to mobile terminals(MTs),achieved through a terrestrial complementary ground station(CGS) wi...In this paper,we study the advantages of cooperation in broadcasting systems from a geosynchronous earth orbit(GEO)satellite to mobile terminals(MTs),achieved through a terrestrial complementary ground station(CGS) with fixed installment,which acts as a relay.Moreover and in the context of the digital video broadcasting-satellite-to-handheld(DVB-SH) standard,the performance improvements offered by the rotated constellations method are investigated,where prior transmission,a phase rotation of the transmitted symbols by a fixed angle is applied followed by a random component interleaver.Turbo codes with soft decision decoding and appropriate random channel interleavers are also considered.We present analytical expressions for the bit log-likelihood ratios(LLRs)that are needed for soft decision decoding at the MT turbo decoder,while the code combining technique is adapted to improve the end-to-end(E2E) performance.Then,we obtain through extensive computer simulations the average bit error probability(ABEP) of quadrature phase-shift keying(QPSK) signals received over pure land-mobile satellite(LMS)and pure CGS links for coding rates 1/3 and6/7.Moreover,the optimal rotation angles are obtained for both links.E2 E ABEP results are then presented assuming cooperation between GEO and CGS,while the power allocation issue is investigated under fixed total transmission power.Our performance evaluation results show that by using the constellation rotation technique,a performance gain can be achieved for high coding rates.展开更多
We put forth a project, that is: using the backscatter technique to realize adaptive long-distance HF broadcasting system in order to improve the quality of HF broadcasting. Then, we analyze errors of the system due t...We put forth a project, that is: using the backscatter technique to realize adaptive long-distance HF broadcasting system in order to improve the quality of HF broadcasting. Then, we analyze errors of the system due to the deviation of the ionospheric parameters' prediction. From the analysis, we draw the conclusion that our project is feasible. In addition, we point out that we can use frequency-spreading and information-coding technique to acquire more clear ionograms. We also offer a judgment on how to choose the control propagation mode on condition of multihop and the existence of more than one propagation mode on the signals' path.展开更多
With the rapid development of the modem information technologies,to promote the education informatization and share the educational and teaching resources,the live classroom in the distance education emerges as the ti...With the rapid development of the modem information technologies,to promote the education informatization and share the educational and teaching resources,the live classroom in the distance education emerges as the times require.The live classroom expands the space-time boundaries in our education and teaching,and changes the traditional teaching methods.It is a new model of the distance education.In order to recognize and understand the impact of the live teaching on the dance teaching and promote the development of the live teaching in the dance education,this paper,from the perspective of the distance education,uses the theories and methods of the distance education to analyze the characteristics of the live teaching,which is a feasible way.展开更多
Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits....Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits. The normal digital TV receiver can only receive and decode the pay TV programs scrambled by one specific CAS. In this paper, the authors proposed a smartcard conditional access interface (SCAI) scheme in order to make the digital TV receiver be a common receiving platform independent of any specific CAS employed at the broadcasting head-end. As a result, it only needs to include a common condi-tional access software package (CCAP) without any requirement of hardware modification in the receiver. Comparison between the two mentioned DVB-CI-based schemes showed that the cost of such kind receiver is greatly reduced. The main design points of the proposed scheme and its reference implementation’s architecture are presented in this paper. This scheme is also one of the candidate national standards for Chinese digital TV broadcasting industry.展开更多
Communication overhead is an important factor in massively parallel processing systems and it has a dramatic influence on the performance of systems. If it can be implemented as quickly as possible, then the performan...Communication overhead is an important factor in massively parallel processing systems and it has a dramatic influence on the performance of systems. If it can be implemented as quickly as possible, then the performance of systems can be greatly improved. Based on the TORUS interconnection network, this paper presents the pipelining broadcasting, which reduces the broadcasting delay and improve the performance of systems.展开更多
In the process of promoting social development, science and technology undoubtedly played a huge role, bringing earth-shaking changes to the improvement of China's economic level and social modernization. The wide...In the process of promoting social development, science and technology undoubtedly played a huge role, bringing earth-shaking changes to the improvement of China's economic level and social modernization. The wide application of computer information technology has changed people's life style to a great extent, especially the automation and intelligent design brought by this technology has made production and life more convenient. As for the monitoring system of the radio transmitting station, due to the adoption of the automatic design, its human labor is fully saved, the maintenance cost is effectively reduced, meanwhile, the labor productivity is fully improved, which points out a new direction for the development of the radio transmitting station in the current society.展开更多
Dream-Building in Tangwangcheng Chief Director:Chen Xichan Length:Four Episodes Producers:The Third Division of Xinjiang Production and Construction Corps and Hunan Broadcasting System Broadcasting Platforms:Mango TV,...Dream-Building in Tangwangcheng Chief Director:Chen Xichan Length:Four Episodes Producers:The Third Division of Xinjiang Production and Construction Corps and Hunan Broadcasting System Broadcasting Platforms:Mango TV,Tencent Video,Youku,and bilibili.展开更多
In order to enhance the accuracy and reliability of wireless location under non-line-of-sight （NLOS） environments,a novel neural network （NN） location approach using the digital broadcasting signals is presented. ...In order to enhance the accuracy and reliability of wireless location under non-line-of-sight （NLOS） environments,a novel neural network （NN） location approach using the digital broadcasting signals is presented. By the learning ability of the NN and the closely approximate unknown function to any degree of desired accuracy,the input-output mapping relationship between coordinates and the measurement data of time of arrival （TOA） and time difference of arrival （TDOA） is established. A real-time learning algorithm based on the extended Kalman filter （EKF） is used to train the multilayer perceptron （MLP） network by treating the linkweights of a network as the states of the nonlinear dynamic system. Since the EKF-based learning algorithm approximately gives the minimum variance estimate of the linkweights,the convergence is improved in comparison with the backwards error propagation （BP） algorithm. Numerical results illustrate thatthe proposedalgorithmcanachieve enhanced accuracy,and the performance ofthe algorithmis betterthanthat of the BP-based NN algorithm and the least squares （LS） algorithm in the NLOS environments. Moreover,this location method does not depend on a particular distribution of the NLOS error and does not need line-of-sight （ LOS ） or NLOS identification.展开更多
Attention,All Villagers Chief Director:Jin Ying Length:Five Episodes Producer:bilibili Broadcasting Platform:bilibili This film series tells the stories of the new generation of farmers in China in a vibrant narrative...Attention,All Villagers Chief Director:Jin Ying Length:Five Episodes Producer:bilibili Broadcasting Platform:bilibili This film series tells the stories of the new generation of farmers in China in a vibrant narrative style.By documenting five villagers’daily lives,each episode highlights the challenges young people are facing in building their life and career in their rural hometowns.展开更多
As the deployment of large Low Earth Orbiters(LEO)communication constellations,navigation from the LEO satellites becomes an emerging opportunity to enhance the existing satellite navigation systems.The LEO navigation...As the deployment of large Low Earth Orbiters(LEO)communication constellations,navigation from the LEO satellites becomes an emerging opportunity to enhance the existing satellite navigation systems.The LEO navigation augmentation(LEO-NA)systems require a centimeter to decimeter accuracy broadcast ephemeris to support high accuracy positioning applications.Thus,how to design the broadcast ephemeris becomes the key issue for the LEO-NA systems.In this paper,the temporal variation characteristics of the LEO orbit elements were analyzed via a spectrum analysis.A non-singular element set for orbit fitting was introduced to overcome the potential singularity problem of the LEO orbits.Based on the orbit characteristics,a few new parameters were introduced into the classical 16 parameter ephemeris set to improve the LEO orbit fitting accuracy.In order to identify the optimal parameter set,different parameter sets were tested and compared and the 21 parameters data set was recommended to make an optimal balance between the orbit accuracy and the bandwidth requirements.Considering the real-time broadcast ephemeris generation procedure,the performance of the LEO ephemeris based on the predicted orbit is also investigated.The performance of the proposed ephemeris set was evaluated with four in-orbit LEO satellites and the results indicate the proposed 21 parameter schemes improve the fitting accuracy by 87.4%subject to the 16 parameters scheme.The accuracy for the predicted LEO ephemeris is strongly dependent on the orbit altitude.For these LEO satellites operating higher than 500 km,10 cm signal-in-space ranging error(SISRE)is achievable for over 20 min prediction.展开更多
Broadcasting is an important operation and been widely used in wireless sensor networks （WSNs）. These networks are power constrained as nodes operate with limited battery power. Wireless sensor networks are spatial ...Broadcasting is an important operation and been widely used in wireless sensor networks （WSNs）. These networks are power constrained as nodes operate with limited battery power. Wireless sensor networks are spatial graphs that have much more clustered and much high path-length characteristics. After considering energy- efficient broadcasting in such networks, by combining the small-world characteristic of WSNs and the properties of ant algorithm to quickly identify an optimal path, small-world power-aware broadcast algorithm is introduced and evaluated. Given different densities of network, simulation results show that our algorithm significantly improves life of networks and also reduces communication distances and power consumption.展开更多
In this paper, we propose a classical secret broadcasting and splitting joint protocol in a quantum scenario. With those genuinely entangled states, the boss can always broadcast some of his secrets and split some oth...In this paper, we propose a classical secret broadcasting and splitting joint protocol in a quantum scenario. With those genuinely entangled states, the boss can always broadcast some of his secrets and split some others to multi- receivers at the same time. The efficiency of the joint protocol is also compared with that of two separate ones which realise classical secret broadcasting and classical secret splitting respectively, and based on the comparison we can see the promising advantage of our joint protocol is that it can realise the two tasks more efficiently and more conveniently.展开更多
Wireless sensor networks （WSNs） consist of sensor nodes that broadcast a message within a network. Efficient broadcasting is a key requirement in sensor networks and has been a focal point of research over the last ...Wireless sensor networks （WSNs） consist of sensor nodes that broadcast a message within a network. Efficient broadcasting is a key requirement in sensor networks and has been a focal point of research over the last few years. There are many challenging tasks in the network, including redundancy control and sensor node localization that mainly depend on broadcasting. In this paper, we propose a broadcasting algorithm to control redundancy and improve localization （BACRIL） in WSNs. The proposed algorithm incorporates the benefits of the gossip protocol for optimizing message broadcasting within the network. Simulation results show a controlled level of redundancy, which is up to 57.6% if the number of sensor nodes deployed in a 500 m×500 m area are increased from 50 to 500.展开更多
The multilevel modulation techniques nf M-Differential Amplitude Phase Shift Keying (DAPSK) have been proposed in combination with Turbo code scheme for digital radio broadcasting bands below 30 MHz radio channel. Com...The multilevel modulation techniques nf M-Differential Amplitude Phase Shift Keying (DAPSK) have been proposed in combination with Turbo code scheme for digital radio broadcasting bands below 30 MHz radio channel. Comparison of this modulation method with channel coding in an Additive White Gaussian Noise (AWGN) and multi-path fading channels has been presented. The analysis provides an iterative decoding of the Turbo code.展开更多
As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliabilit...As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliability by adopting flexible frame structure and advanced forward error correction coding compared with the 1 st generation DTTB systems.In order to increase the flexibility and robustness of the DTTB network,the frequency reuse scheme of factor one(reuse-1)is proposed,where the same RF channel is used by different stations covering the adjacent service areas.However,it demands a very low carrier-tonoise ratio(C/N)threshold below 0 dB at the DTTB physical layer.In this paper,a robust broadcasting technique is proposed based on DTMB-A with newly designed low-rate low density parity check(LDPC)codes.By adopting quasi-cyclic(QC)Raptor-like structure and progressive lifting method,the high performance low-rate LDPC codes are designed supporting multiple code lengths.Both density-evolution analyses and laboratory measurements demonstrate that DTMB-A with low-rate coding can complete the demodulation reliably with the C/N threshold below0 d B,which is one important necessary condition to support frequency reuse-1 scheme.展开更多
In the era of network live broadcasting for everyone,the development of live broadcasting platforms is also more intelligent and diversified.However,in the face of a large group of elderly users,the interface interact...In the era of network live broadcasting for everyone,the development of live broadcasting platforms is also more intelligent and diversified.However,in the face of a large group of elderly users,the interface interaction design mode used is still mainly based on the interaction mode for young groups,and is not designed for elderly users.Therefore,a design method for optimizing the interaction interface of live broadcasting platform for elderly users was proposed in this study.Firstly,the case study method and Delphi expert survey method were used to determine the design needs of elderly users and the design mode was analysed.Secondly,the orthogonal design principle was used to design a test sample of the interactive interface of live broadcasting platform applicable for the elderly users,and then a user evaluation system was established to calculate the weights of the design elements using hierarchical analysis,and then the predictive relationship between the design mode of the interactive interface of live broadcasting platform and the elderly users was established by Quantitative Theory I.Finally,Genetic Algorithm was applied to generate the optimized design scheme.The results showed that the design method based on the Genetic Algorithm and the combination of Quantitative Theory can scientifically and effectively optimize the design of the interactive interface of the live broadcasting platform for the elderly users,and improve the experience of the elderly users.展开更多
With the increasing popularity of solid sate lighting devices, Visible Light Communication (VLC) is globally recognized as an advanced and promising technology to realize short-range, high speed as well as large capac...With the increasing popularity of solid sate lighting devices, Visible Light Communication (VLC) is globally recognized as an advanced and promising technology to realize short-range, high speed as well as large capacity wireless data transmission. In this paper, we propose a prototype of real-time audio and video broadcast system using inexpensive commercially available light emitting diode (LED) lamps. Experimental results show that real-time high quality audio and video with the maximum distance of 3 m can be achieved through proper layout of LED sources and improvement of concentration effects. Lighting model within room environment is designed and simulated which indicates close relationship between layout of light sources and distribution of illuminance.展开更多
文摘Digital broadcasting system has become a high-light of research on computer application. To respond to the changes of the playbill in the broadcasting system in real time, the response time of the system must be studied. There is scarcely the research on this area currently. The influence factors in the response time are analyzed; the model on the response time of the system service is built; how the influence factors affect the response time of the system service is validated; and four improvement measures are proposed to minimize the response time of system service.
基金Support to the SatNEx-Ⅲ Network of Experts (SatNEx-Ⅲ) CoO2,2011-2012
文摘In this paper,we study the advantages of cooperation in broadcasting systems from a geosynchronous earth orbit(GEO)satellite to mobile terminals(MTs),achieved through a terrestrial complementary ground station(CGS) with fixed installment,which acts as a relay.Moreover and in the context of the digital video broadcasting-satellite-to-handheld(DVB-SH) standard,the performance improvements offered by the rotated constellations method are investigated,where prior transmission,a phase rotation of the transmitted symbols by a fixed angle is applied followed by a random component interleaver.Turbo codes with soft decision decoding and appropriate random channel interleavers are also considered.We present analytical expressions for the bit log-likelihood ratios(LLRs)that are needed for soft decision decoding at the MT turbo decoder,while the code combining technique is adapted to improve the end-to-end(E2E) performance.Then,we obtain through extensive computer simulations the average bit error probability(ABEP) of quadrature phase-shift keying(QPSK) signals received over pure land-mobile satellite(LMS)and pure CGS links for coding rates 1/3 and6/7.Moreover,the optimal rotation angles are obtained for both links.E2 E ABEP results are then presented assuming cooperation between GEO and CGS,while the power allocation issue is investigated under fixed total transmission power.Our performance evaluation results show that by using the constellation rotation technique,a performance gain can be achieved for high coding rates.
文摘We put forth a project, that is: using the backscatter technique to realize adaptive long-distance HF broadcasting system in order to improve the quality of HF broadcasting. Then, we analyze errors of the system due to the deviation of the ionospheric parameters' prediction. From the analysis, we draw the conclusion that our project is feasible. In addition, we point out that we can use frequency-spreading and information-coding technique to acquire more clear ionograms. We also offer a judgment on how to choose the control propagation mode on condition of multihop and the existence of more than one propagation mode on the signals' path.
文摘With the rapid development of the modem information technologies,to promote the education informatization and share the educational and teaching resources,the live classroom in the distance education emerges as the times require.The live classroom expands the space-time boundaries in our education and teaching,and changes the traditional teaching methods.It is a new model of the distance education.In order to recognize and understand the impact of the live teaching on the dance teaching and promote the development of the live teaching in the dance education,this paper,from the perspective of the distance education,uses the theories and methods of the distance education to analyze the characteristics of the live teaching,which is a feasible way.
基金Project (No. 200442) supported by the Electronics DevelopmentFoundation for the Key Industrialization Project of the Ministry of0Information Industry, China
文摘Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits. The normal digital TV receiver can only receive and decode the pay TV programs scrambled by one specific CAS. In this paper, the authors proposed a smartcard conditional access interface (SCAI) scheme in order to make the digital TV receiver be a common receiving platform independent of any specific CAS employed at the broadcasting head-end. As a result, it only needs to include a common condi-tional access software package (CCAP) without any requirement of hardware modification in the receiver. Comparison between the two mentioned DVB-CI-based schemes showed that the cost of such kind receiver is greatly reduced. The main design points of the proposed scheme and its reference implementation’s architecture are presented in this paper. This scheme is also one of the candidate national standards for Chinese digital TV broadcasting industry.
文摘Communication overhead is an important factor in massively parallel processing systems and it has a dramatic influence on the performance of systems. If it can be implemented as quickly as possible, then the performance of systems can be greatly improved. Based on the TORUS interconnection network, this paper presents the pipelining broadcasting, which reduces the broadcasting delay and improve the performance of systems.
文摘In the process of promoting social development, science and technology undoubtedly played a huge role, bringing earth-shaking changes to the improvement of China's economic level and social modernization. The wide application of computer information technology has changed people's life style to a great extent, especially the automation and intelligent design brought by this technology has made production and life more convenient. As for the monitoring system of the radio transmitting station, due to the adoption of the automatic design, its human labor is fully saved, the maintenance cost is effectively reduced, meanwhile, the labor productivity is fully improved, which points out a new direction for the development of the radio transmitting station in the current society.
文摘Dream-Building in Tangwangcheng Chief Director:Chen Xichan Length:Four Episodes Producers:The Third Division of Xinjiang Production and Construction Corps and Hunan Broadcasting System Broadcasting Platforms:Mango TV,Tencent Video,Youku,and bilibili.
基金The National High Technology Research and Development Program of China (863 Program) (No.2008AA01Z227)the Cultivatable Fund of the Key Scientific and Technical Innovation Project of Ministry of Education of China (No.706028)
文摘In order to enhance the accuracy and reliability of wireless location under non-line-of-sight （NLOS） environments,a novel neural network （NN） location approach using the digital broadcasting signals is presented. By the learning ability of the NN and the closely approximate unknown function to any degree of desired accuracy,the input-output mapping relationship between coordinates and the measurement data of time of arrival （TOA） and time difference of arrival （TDOA） is established. A real-time learning algorithm based on the extended Kalman filter （EKF） is used to train the multilayer perceptron （MLP） network by treating the linkweights of a network as the states of the nonlinear dynamic system. Since the EKF-based learning algorithm approximately gives the minimum variance estimate of the linkweights,the convergence is improved in comparison with the backwards error propagation （BP） algorithm. Numerical results illustrate thatthe proposedalgorithmcanachieve enhanced accuracy,and the performance ofthe algorithmis betterthanthat of the BP-based NN algorithm and the least squares （LS） algorithm in the NLOS environments. Moreover,this location method does not depend on a particular distribution of the NLOS error and does not need line-of-sight （ LOS ） or NLOS identification.
文摘Attention,All Villagers Chief Director:Jin Ying Length:Five Episodes Producer:bilibili Broadcasting Platform:bilibili This film series tells the stories of the new generation of farmers in China in a vibrant narrative style.By documenting five villagers’daily lives,each episode highlights the challenges young people are facing in building their life and career in their rural hometowns.
基金the National Natural Science Foundation of China[grant number 42074036]the Fundamental Research Funds for the Central Universities.
文摘As the deployment of large Low Earth Orbiters(LEO)communication constellations,navigation from the LEO satellites becomes an emerging opportunity to enhance the existing satellite navigation systems.The LEO navigation augmentation(LEO-NA)systems require a centimeter to decimeter accuracy broadcast ephemeris to support high accuracy positioning applications.Thus,how to design the broadcast ephemeris becomes the key issue for the LEO-NA systems.In this paper,the temporal variation characteristics of the LEO orbit elements were analyzed via a spectrum analysis.A non-singular element set for orbit fitting was introduced to overcome the potential singularity problem of the LEO orbits.Based on the orbit characteristics,a few new parameters were introduced into the classical 16 parameter ephemeris set to improve the LEO orbit fitting accuracy.In order to identify the optimal parameter set,different parameter sets were tested and compared and the 21 parameters data set was recommended to make an optimal balance between the orbit accuracy and the bandwidth requirements.Considering the real-time broadcast ephemeris generation procedure,the performance of the LEO ephemeris based on the predicted orbit is also investigated.The performance of the proposed ephemeris set was evaluated with four in-orbit LEO satellites and the results indicate the proposed 21 parameter schemes improve the fitting accuracy by 87.4%subject to the 16 parameters scheme.The accuracy for the predicted LEO ephemeris is strongly dependent on the orbit altitude.For these LEO satellites operating higher than 500 km,10 cm signal-in-space ranging error(SISRE)is achievable for over 20 min prediction.
文摘Broadcasting is an important operation and been widely used in wireless sensor networks （WSNs）. These networks are power constrained as nodes operate with limited battery power. Wireless sensor networks are spatial graphs that have much more clustered and much high path-length characteristics. After considering energy- efficient broadcasting in such networks, by combining the small-world characteristic of WSNs and the properties of ant algorithm to quickly identify an optimal path, small-world power-aware broadcast algorithm is introduced and evaluated. Given different densities of network, simulation results show that our algorithm significantly improves life of networks and also reduces communication distances and power consumption.
文摘In this paper, we propose a classical secret broadcasting and splitting joint protocol in a quantum scenario. With those genuinely entangled states, the boss can always broadcast some of his secrets and split some others to multi- receivers at the same time. The efficiency of the joint protocol is also compared with that of two separate ones which realise classical secret broadcasting and classical secret splitting respectively, and based on the comparison we can see the promising advantage of our joint protocol is that it can realise the two tasks more efficiently and more conveniently.
文摘Wireless sensor networks （WSNs） consist of sensor nodes that broadcast a message within a network. Efficient broadcasting is a key requirement in sensor networks and has been a focal point of research over the last few years. There are many challenging tasks in the network, including redundancy control and sensor node localization that mainly depend on broadcasting. In this paper, we propose a broadcasting algorithm to control redundancy and improve localization （BACRIL） in WSNs. The proposed algorithm incorporates the benefits of the gossip protocol for optimizing message broadcasting within the network. Simulation results show a controlled level of redundancy, which is up to 57.6% if the number of sensor nodes deployed in a 500 m×500 m area are increased from 50 to 500.
基金Supported by the National Natural Science Foundation of China (No.60072013)
文摘The multilevel modulation techniques nf M-Differential Amplitude Phase Shift Keying (DAPSK) have been proposed in combination with Turbo code scheme for digital radio broadcasting bands below 30 MHz radio channel. Comparison of this modulation method with channel coding in an Additive White Gaussian Noise (AWGN) and multi-path fading channels has been presented. The analysis provides an iterative decoding of the Turbo code.
基金supported in part by the National Natural Science Foundation of China(NSFC)under Grant 61931015the Peng Cheng Laboratory under Grant PCL2021A10+1 种基金the Science,Technology and Innovation Commission of Shenzhen Municipality(No.JSGG20201103095805015)sponsored by Tsinghua University-Yunnan Mobile Digital TV Company Ltd.,Joint Research Center(JCICBN)。
文摘As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliability by adopting flexible frame structure and advanced forward error correction coding compared with the 1 st generation DTTB systems.In order to increase the flexibility and robustness of the DTTB network,the frequency reuse scheme of factor one(reuse-1)is proposed,where the same RF channel is used by different stations covering the adjacent service areas.However,it demands a very low carrier-tonoise ratio(C/N)threshold below 0 dB at the DTTB physical layer.In this paper,a robust broadcasting technique is proposed based on DTMB-A with newly designed low-rate low density parity check(LDPC)codes.By adopting quasi-cyclic(QC)Raptor-like structure and progressive lifting method,the high performance low-rate LDPC codes are designed supporting multiple code lengths.Both density-evolution analyses and laboratory measurements demonstrate that DTMB-A with low-rate coding can complete the demodulation reliably with the C/N threshold below0 d B,which is one important necessary condition to support frequency reuse-1 scheme.
文摘In the era of network live broadcasting for everyone,the development of live broadcasting platforms is also more intelligent and diversified.However,in the face of a large group of elderly users,the interface interaction design mode used is still mainly based on the interaction mode for young groups,and is not designed for elderly users.Therefore,a design method for optimizing the interaction interface of live broadcasting platform for elderly users was proposed in this study.Firstly,the case study method and Delphi expert survey method were used to determine the design needs of elderly users and the design mode was analysed.Secondly,the orthogonal design principle was used to design a test sample of the interactive interface of live broadcasting platform applicable for the elderly users,and then a user evaluation system was established to calculate the weights of the design elements using hierarchical analysis,and then the predictive relationship between the design mode of the interactive interface of live broadcasting platform and the elderly users was established by Quantitative Theory I.Finally,Genetic Algorithm was applied to generate the optimized design scheme.The results showed that the design method based on the Genetic Algorithm and the combination of Quantitative Theory can scientifically and effectively optimize the design of the interactive interface of the live broadcasting platform for the elderly users,and improve the experience of the elderly users.
文摘With the increasing popularity of solid sate lighting devices, Visible Light Communication (VLC) is globally recognized as an advanced and promising technology to realize short-range, high speed as well as large capacity wireless data transmission. In this paper, we propose a prototype of real-time audio and video broadcast system using inexpensive commercially available light emitting diode (LED) lamps. Experimental results show that real-time high quality audio and video with the maximum distance of 3 m can be achieved through proper layout of LED sources and improvement of concentration effects. Lighting model within room environment is designed and simulated which indicates close relationship between layout of light sources and distribution of illuminance.
